DESCRIPTION: (Verbatim from application) Rupture of the anterior cruciate injury typically occurs during a rapid deceleration or change of direction, without contact with other players. Landing, stopping, and sidestepping are typical examples of such movements. Surgical repair is costly and requires extensive rehabilitation. The long-term prognosis is a high risk of osteoarthritis, which may eventually lead to total knee replacement. Women have a two to seven times larger risk for ACL injury in sport than men. Many factors play a role in the injury mechanism: anatomy, tissue strength, hormonal effects, equipment (footwear) design, and movement coordination. The latter two factors are amenable to intervention and offer potential prevention strategies. However, specific quantitative knowledge of their effects on ACL injury is not available and a controlled experimental study of the injury mechanisms is required. Such studies cannot be performed in human subjects, for ethical reasons. Animal models are unsuitable because these do not simulate the mechanics of the movement. On the other hand, the mechanical properties of the musculoskeletal system are sufficiently well known to make computer simulations feasible. Hence, the objectives of this project are (1) to develop valid computational models for ACL injury during stopping, landing, and cutting movements, (2) to use these models to determine the effects of variations in movement control on the rate of ACL injury during these movements, and (3) to predict the protective effect of specific modifications of shoe friction on rate of ACL injury and the associated effect on performance. We expect to find that inaccuracies in movement coordination, as observed in human subjects, can lead to ACL rupture and that that this explains the larger risk for females. Further more, we expect to find that these injuries can be effectively prevented by coordination training or reduction of shoe-ground friction coefficients for females. A secondary hypothesis is that the desired modifications can be achieved without impairing performance. Results of this research can be translated into recommendations and specific goals for coordination training, making it possible to use biofeedback, and development of gender-specific footwear safety standards for female athletes. The long-term impact on public health is a reduction in knee ligament injuries in sport, especially in females, and the ensuing long-term disabilities due to osteoarthritis in a relatively young population.